The Ferguson City Council unanimously approved a proposal with the U.S. Department of Justice on Tuesday to overhaul the city's police department, an agreement the city effectively rejected six weeks ago, provoking a federal lawsuit.

The decision was punctuated by cheers from the crowd and then a hug between Ferguson Mayor James Knowles III and Michael Brown Sr., the father of the 18-year-old whose death led to protests, federal investigations and now one of the most comprehensive agreements ever to reform a police department and municipal court.

"This is Mike Brown's legacy," said Brown Sr. of his son, Michael Brown Jr. who was fatally shot by a Ferguson police officer on Aug. 9, 2014.

Although the vote was unanimous, one council member was out sick.

The council's reversal has mostly been attributed to a March 4 letter from Vanita Gupta, head of the Justice Department's Civil Rights Division, which suggested the projected costs of the reforms had been overstated.

Finance Director Jeffrey Blume had projected the costs of abiding by the agreement to be as high as $3.7 million in the first year alone.

But that figure was based partly on a provision in the agreement that required Ferguson to offer police competitive salaries.

Blume interpreted the provision to mean that officers and other employees must receive 25 percent pay increases.

The figures triggered accusations that the city had inflated the numbers to stoke fear and provide certain council members a pretext to vote down the agreement, called a consent decree.

Gupta's letter rebutted the conclusions drawn by Blume, arguing that the department had always made it clear that salary increases could come over time and that the agreement itself does not specify any particular percentage.

"Tonight, the city of Ferguson, Missouri, took an important step towards guaranteeing all of its citizens the protections of our Constitution," Gupta said in a statement on Tuesday. "We are pleased that they have approved the consent decree, a document designed to provide the framework needed to institute constitutional policing in Ferguson, and look forward to filing it in court in the coming days and beginning to work with them towards implementation."

This week the city released revised estimates of the costs of the reforms, projected them to be between $1 million and $1.5 million in the first year, $782,500 and $882,300 in the second year and $682,092 and $754,350 every year there after.

The city, which faces a $2.8 million budget deficit, is expected to operate under the agreement for three to five years.

Knowles stressed the importance of residents supporting a economic development sales tax and property tax increase _ both proposals on the April ballot.

"Without passing this tax increase, it will be nearly impossible to meet the terms of that decree," Knowles said.

The city has a $14.5 million operating budget.

Although the officer who shot Brown was never charged, the teenager's death led to an investigation into the practices of the Ferguson Police Department.

The Justice Department released the findings of that investigation more than a year ago, detailing numerous constitutional violations _ searches without reasonable suspicion, arrests without probable cause and force used unnecessarily.

The DOJ also accused Ferguson of using its municipal court for revenue, not justice.

The two parties negotiated for months. Then in January the city released the agreement, which contained extensive reforms _ new use-of-force policies for police, hours of additional training for officers, body camera requirements and a plan for community policing.

Last month, the council voted to accept the decree, but only with certain conditions, one of which would have effectively diluted its power.

The city sought to eliminate the so-called "poison pill" clause that made the decree apply to any other agency providing policing in Ferguson. The revision allowed Ferguson to circumvent most of the decree by disbanding its police department.

The Justice Department sued the city the next day.

But at that same meeting, council members also appointed Laverne Mitchom, a retired educator, to fill a council seat vacated when Brian Fletcher, a former mayor died of a heart attack in January.

Fletcher had founded the "I love Ferguson" campaign and never passed up a chance to extol the city's virtues.

Mitchom, on the other hand, had participated in the protests over Brown's death.

"We may not always agree on everything," Mitchom said Tuesday. "But this evening I feel very hopeful that one thing we agree on is that we must come together and do what's best for the overall good of all of us in this community."

Over the past six weeks, the council's meetings have been marked by protest _ demonstrations that have been both quiet and loud.

On Tuesday, activists arrived with shoeboxes full of symbolic gag gifts for city officials: pacifiers to keep them from whining, calculators to help them provide correct numbers and laxatives as a statement about what some leaders are full of.

"Some of the protesters have brought you all thank you gifts for finally taking this step," said activist Keith Rose. "We hope that you will accept them."

He added that the protests have shown that "You can fight City Hall, but City Hall can't fight justice."

Councilman Wesley Bell agreed with Rose, at least on one point.

Approving the consent decree was "a step forward," Bell said. Hard work remains and the city needs to heal, he said.

"Ferguson has been the emotional ground zero of this issue," he said. "In many ways we are trying to repair a tear in the fabric of our city. ... The fact that the world is watching us gives us an opportunity to show what change can look like."